The invention is a telephone line interface employed for coupling an electronic device, hereinafter main module, to a public telephone (PT) network, and is, therefore, subject to a large set of telephone interconnect regulations. Examples of such main modules include modems, telephone message systems, video-text storage systems, or, as in the preferred embodiment, a text-to-speech device. In the United States and Canada, meeting these regulations is quite straightforward (the regulations in the United States and Canada are essentially the same). However, in the rest of the world, there are many countries with different (and frequently changing) regulations. Additionally, the regulations can be plain barrier regulations.
In general, the problem of PT interconnect is solved by modifying the main module to conform to a particular country's regulations. In every prior solution, the main module is involved in some way with making the system conform to the regulatory issues. This coupling is unpleasant. A dependency between the main module and an option module is disadvantageous because it means that the option module may have to be recertified any time a change to the the main module is made. Since the base module changes with each language, many different combinations of base module and option module are possible.